/Engine/Plugins/Experimental/TextToSpeech/Source/TextToSpeech/Public/TextToSpeechEngineSubsystem.h
Return true when the targeted text to speech channel is vocalising, otherwise false.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category=TextToSpeech) bool IsSpeakingOnChannel ( [FName](API\Runtime\Core\UObject\FName) InChannelId ) const